Andy, you are the hero of the day!  Thank you so much!

Thinking about it, that explains why Quicklisp does not have a problem with it:
it always loads the .asd file I suppose.  (I haven't checked the code.)

I'll keep on packaging Next, hopefully there won't be such an obstacle again and
we will see it land in Guix very soon!

Cheers!

-- 
Pierre Neidhardt
https://ambrevar.xyz/